Limited data suggest that HIV infection and its treatment are associated with hearing loss. Several factors can affect hearing in those infected with HIV including HIV itself, secondary infections, and medications. The relative contribution of these factors is not known. We will bring together four established Dartmouth/Tanzanian resources to study hearing loss among both HIV-infected adults and children in Tanzania: 1) the DarDar Health Study, an ongoing NIH-funded study of HIV-associated tuberculosis involving Dartmouth Medical School (DMS) and the Muhimbili University of Health and Allied Sciences (MUHAS), which will provide a large cohort of HIV-infected adult study subjects, 2) the MUHAS ENT service, which routinely diagnoses and treats HIV-infected individuals with hearing loss, 3) the DarDar pediatric clinic, a DMS/MUHAS collaboration to diagnose and treat HIV-positive children, which follows a growing cohort of HIV-positive and HIV-affected children and 4) a laptop computer- based, hearing-testing system developed by DMS in collaboration with the National Aeronautics and Space Administration for use on the International Space Station, which will be used as the field testing apparatus. This battery-powered, laptop-based device incorporates Bikisy-like tracking audiometry, distortion-product otoacoustic emission testing, probe placement verification, in-ear noise level measurement, and a gap detection test. It is ideally suited for assessing hearing loss in resource-limited environments. A computer-based, Kiswahili questionnaire that covers hearing symptoms and noise exposure will be added to the system to provide a robust system for performing complete hearing evaluations efficiently. Using this system we will determine the frequency of abnormal central and peripheral hearing test results in both adults and children by performing a cross-sectional prevalence study in Tanzania among HIV-positive subjects receiving and not receiving anti-retroviral therapy (ART), HIV-positive subjects with and without prior treatment for TB, and HIV-negative controls. We will also assess the incidence of new hearing loss and the quantitative contributions of HIV severity, ART duration and specific TB treatment regimens to hearing loss in a longitudinal study among HIV-positive and HIV-negative subjects. African-made hearing aids with solar battery chargers will be provided to those subjects with significant hearing loss that would benefit from hearing augmentation. Collectively, these studies will: (1) provide the first comprehensive data on hearing loss among HIV-positive adults and children living in a resource poor setting, (2) provide information on the prevalence, incidence and nature (central vs. peripheral) of the hearing loss in HIV-positive subjects, (3) determine associations between hearing loss, ART and TB treatment, and (4) permit the development of guidelines for monitoring high-risk subjects and intervening with appropriate treatment and hearing augmentation.